A conventional interleaving method is described in below-mentioned Patent document 1. For example, when a concatenated code of an RS code and a convolutional code is used as an error-correcting code, a communication device that transmits a signal by using OFDM (Orthogonal Frequency Division Multiplexing) subjects a received signal to FFT, performs frequency deinterleaving on the received signal, and further performs time deinterleaving on the frequency-deinterleaved signal. Information for I axis and information for Q axis after the time deinterleaving is performed are demapped into information for the number of modulation points according to a modulation method. It is noted that the modulation method is previously specified for each block formed of n numbers of carriers of one OFDM symbol, and that the demapping is performed for each segmented block.
The demapped information is divided into a plurality of layers, and bit deinterleaving is performed on the respective layers to improve error resilience in the convolutional code. Thereafter, convolutional decoding is performed thereon. Then, the result of convolutional decoding is divided into a plurality of layers, and a byte deinterleaving process is performed on the respective layers to improve error resilience in the RS code. Further, an RS decoding process is performed on a byte-deinterleaved sequence and the result of decoding is output.
Patent document 1: Japanese Patent Application Laid-open No. 2002-217860